A Low-Code Orchestration Middleware for Secure and Transparent IoT–Blockchain Integration

The integration of Internet of Things (IoT) infrastructures with Distributed Ledger Technologies (DLT) remains challenging due to the reliance on complex, tightly coupled back-end systems or centralized oracle services that hinder scalability, maintainability, and trust. This paper introduces a lightweight middleware architecture based on a Low-Code Development Platform (LCDP) that enables flexible and secure IoT-to-blockchain orchestration. We develop a custom workflow extension for the n8n platform that supports direct interaction with smart contracts, thereby removing the need for third-party oracle intermediaries. The proposed system was evaluated in a real-world deployment involving a network of Netatmo environmental sensors and the Alastria consortium blockchain. Experimental results show that the middleware can process 12 concurrent sensor data streams with an average end-to-end latency of 37.4 s, a delay dominated by the blockchain consensus time rather than middleware overhead, while ensuring the generation of immutable and verifiable audit trails. These findings demonstrate that low-code orchestration can deliver an effective, scalable, and fault-tolerant alternative for integrating IoT infrastructures with blockchain in Industry 4.0 environments.